1. Field of the Invention
The present invention relates to a phase change ink composition and a conductive pattern formed using the same, and more particularly, to a phase change ink composition that has a low melting temperature ranging from 60° C. to 90° C., thus enabling the use of a typical inkjet head, and a conductive pattern formed using the same.
2. Description of the Related Art
Optical patterning using a lithography process has been widely used as a general process for forming a conductive pattern. Optical patterning, however, has complicated process steps incurring relatively high costs, and may harmful gas and waste water formed during exposure and etching processes thereof may be discharged, leading to environmental pollution. Therefore, low cost, environmentally-friendly pattern forming methods have been studied, and among such methods, a representative example is an inkjet printing method.
Since the inkjet printing method is a method of directly transferring a desired pattern to a substrate, it has simple process steps, facilitates large-scale printing, reduces processing time, and saves manufacturing costs. Also, since the inkjet printing method does not require an exposure process and an etching process, unlike an existing optical patterning method, it is an environmentally-friendly patterning method that does not discharge environmental pollutants.
To form a conductive pattern using the inkjet printing method, a conductive ink with a low viscosity able to form a conductive line is needed, and for this purpose, conductive metal nanoparticles are used as a material for an ink composition.
However, in the case in which the metal nanoparticles are used as a material for an ink composition, the specific gravity of a metal is higher than an organic solvent, so that the metal nanoparticles may be precipitated to thus deteriorate the storage stability.
Decreasing the size of the metal nanoparticles is effective in decreasing the settling speed thereof by Brownian motion, but is not a fundamental solution. Also, there exists a method of continuously using a stirrer so as to prevent metal nanoparticles from settling, but since the method requires the continuous operation of the stirrer, a cost increase may be incurred.
An increase in the viscosity of ink may reduce the settling speed of the metal nanoparticles, and further by solidifying the ink, the settling of the metal nanoparticles may be stopped completely. Therefore, studies into an ink composition having a solid state at room temperature but a liquid state in a temperature rise range allowed by an inkjet device, and able to maintain a viscosity of not more than 20 cP at a jetting temperature have been undertaken.
Thus, an ink composition containing a phase change ink of a wax component as a main component has been developed, and the ink composition has a melting temperature exceeding 90° C. To meet the melting temperature of the ink composition, the inkjet head should be maintained at a temperature not lower than 100° C. in consideration of a temperature allowance of the inkjet head; however, such a temperature is higher than 90° C., the temperature allowance of most inkjet heads. Therefore, the phase change ink should only be used for a specially designed inkjet head. Also, the wax component, a main component of the ink composition is mostly nonpolar, insoluble in water, and is only soluble in a nonpolar solvent. Therefore, in the case in which a polar additive used in a general ink is added to the ink composition, the polar additive may not be well mixed, so that a phase separation may be caused.